<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var num1=prompt("请您输入第一个数字");
    var num2=prompt("请您输入第二个数字");
    var num3=prompt("请您输入运算符号");
    if(num3=="+"){
        alert(parseInt(num1)+parseInt(num2));
    }else if(num3=="-"){
        alert(parseInt(num1)-parseInt(num2));
    }else if(num3=="*"){
        alert(parseInt(num1)*parseInt(num2));
    }else if(num3=="/"){
        alert(parseInt(num1)/parseInt(num2));
    }else{
        alert("亲，输错了哟！！！")
    }

</script>

</body>
</html>